Oral Presentation Advances in Neuroblastoma Research Congress 2016

Engineered Neuroblastoma Cellular Immunotherapy (ENCIT)-01: A phase 1 study of autologous T-cells lentivirally transduced to express CD171-specific Chimeric Antigen Receptors (CAR) for recurrent/refractory high-risk neuroblastoma (HR-NB) (#105)

Julie R Park 1 , Annette Kuenkele 2 , Rebecca Gardner 1 , Olivia Finney 3 , Hannah Smithers 3 , Laura Finn 1 , Navin Pinto 1 , Christopher Brown 3 , Catherine Lindgren 3 , Assaf P Oron 4 , Michael C Jensen 3
  1. University of Washington, Seattle Children's Hospital, Seattle, WA, United States
  2. Charité - University Hospital Berlin, Berlin, Germany
  3. Seattle Children's Research Institute, Ben Towne Center for Childhood Cancer Research, Seattle, WA, USA
  4. Seattle Children's Research Institute, Seattle, WA, USA

Background. Anti-ganglioside (GD2) antibody immunotherapy improves outcome for HR-NB but 35% of patients recur and off-tumor targeting of neuronal tissue may limit use of GD2 for novel immunotherapy such as CAR T cell therapy. L1-CAM (CD171) is expressed by neuroblastoma and mCE7 recognizes a tumor-specific glycosylated epitope of L1CAM, offering an alternative immunotherapy target for HR-NB.

Methods. Pts with recurrent HR-NB were enrolled to examine the safety and feasibility of administering autologous, peripheral blood (PB)-derived T cells genetically modified using a SIN lentiviral vector to express either scFv-IgG4hinge-CD28tm-4-1BB-zeta (second generation (2G)) or CD171-specific scFv-IgG4hinge-CD28tm/cyto-4-1BB-zeta) (third generation (3G)) CD171 (L1CAM)-specific CAR and the selection/suicide construct EGFRt. Patients received lymphodepleting chemotherapy followed by cryopreserved CD4/EGFRt+ and CD8/EGFRt+ CARs administered at a 1:1 ratio at each dose level. The MTD will be determined for each construct.

Results. From 11/2014 through 1/2016, 14 patients enrolled with CAR manufacturing successful in 12 patients. Seven patients (8.3 years at enrollment; range 7.1-18.7) were treated at dose level 1 (1 X 106 CAR T cells/kg, n=3-2G and n=1-3G); dose level 2 (5 x 106 CAR T cells/kg, n=1-2G) and dose level 3 (1 x 107CAR T cells/kg, n=1-2G). No CAR-associated toxicities have occurred. CAR T cell persistence was not documented by multi-parameter flow evaluation at Dose Level 1. Minimal PB persistence (< 0.5%) was detected at Dose Level 2 while persistence testing is underway at Dose Level 3. No objective responses were observed, 3 pts had stable disease (range 12 – 18 weeks).

Conclusions. It is feasible to harvest and manufacture CAR T cells from heavily pre-treated pts with HR-NB. In contrast to experience with the use of CD19-CAR T cell therapy, the initially planned T cell infusion doses were insufficient to generate persistence in patients with solid tumors who do not have high burden for circulating antigen to stimulate T cell expansion. Higher cell dose cohorts and novel strategies to stimulate CAR expansion are underway.